scent of worm cheese

Bizarre Bites: Maggot Cheese

Picture it: You slice into a a beautiful wheel of cheese. The perfectly aged rind, the pungent rotted diaper scent of coagulated milk, and your ears pick up the teeniest tiniest little squeak, the pitter-patter of little…maggots? That’s right, this midsized wheel of cheese is filled with wriggling and jiggling fly larvae. Maggot cheese, also called casu marzu, is an Italian delicacy most commonly found in the mountainous regions of northern Sardinia. You find similar cheeses in France, Germany, and Nicaragua. I have tried them on two continents and absolutely adore the stuff. I’ll bet most of you would agree with me if you tried it.

Maggots, anyone? (Photo Credit: Travel Channel)

How to Make Maggot Cheese

Step 1: Make a wheel of Pecorino cheese and place mature cheese wheel outdoors.

Step 2: Allow the piophila casei, or cheese fly, to lay eggs in cheese.

Step 3: Wait for the eggs to hatch and the larvae to begin eating the cheese. The cheese is ready for you to eat when it becomes soft and begins to weep its liquid-y goodness. But you won’t see if through the hard aged exterior. Practice makes perfect.

Who cut the cheese? (Photo credit:

Who Cut the Cheese?

Beans aren’t the only “musical fruit.” Lots of other food might lead to toots. The average person will fart, S.B.D. (Silent But Deadly) or otherwise, fourteen times per day. Where does all of that gas come from? Some of it is swallowed air, but the rest is the by-product of food broken down by bacteria in the digestive system. Some foods are more notorious than others for producing thunder down under. Sugary foods tend to be the culprit more often than not and foods high in fiber will just increase the stench.

The scientific name for the gas released in a fart is “flatus.” Flatus is made up of oxygen, nitrogen, hydrogen, carbon dioxide, and the sticker, methane. But every once in a while, a chemical reaction occurs creating hydrogen sulfide, which has a smell reminiscent of rotten eggs.

Just remember this wise idiom before you ask, “Who cut the cheese?”: He who smelt it dealt it.

It’s Alive! Picture it: You slice into a a beautiful wheel of cheese. The perfectly aged rind, the pungent rotted diaper…

The scent of the maggot

The subject may seem redolent of an old music hall joke: “I say, I say, I say, my dog has no nose!” “How does he smell?” “Terrible!”

So begins Dr Matthew Cobb’s explanation of how maggots smell. (Terrible? He would defend them, it’s only the rotting flesh they inhabit that stinks.) The olfactory habits of maggots may sound arcane, but working out how maggots sniff out food could have profound implications for agriculture, as well as furthering our understanding of how our ability to smell actually works.

Cobb, who is at the Laboratoire d’Ecologie in Paris, normally studies adult maggots in the form of fruit flies. “I was always very snotty about maggots because they don’t do much. They’re nothing but a moving bag of genes that has to eat. You can get flies to mate and learn.” Cobb then realised that the maggot’s very simplicity means it is an easier system to understand.

“They have a mindless existence: you starve them and put them in front of a smell and they move towards it.” What better, if smell in maggots is what excites you?

Now that the genome of fruit flies has been unraveled, it’s been discovered that they have 50 different genes which code for 1,200 nerves used to detect smell. But the maggot has only 21 nerves for smell and no one knows which genes are involved. What scientists do know is that none of the genes that allow a fly to develop a sense of smell are used by the maggot. This suggests that all maggots may have the same olfactory system whether they are a blow fly larva or stag beetle grub which developed several million years ago.

How we all smell is a subject that has intrigued the best and brightest minds throughout history. The Greek philosopher Democritus, who conceived the idea of atoms, thought sweet smells were produced by round atoms and sharp scents by pointy ones and, according to Cobb, our understanding hasn’t advanced much.

In the 1660s a Dutch scientist, Jan Swammerdam, tried to figure out how the maggot, this sack of jelly with a mini nervous system and no discernible nose, could smell. His perception is still thought to be astounding more than 400 years later. Maggots have a dorsal organ on their head which is covered in a mucous layer that traps smells. They have proteins that bind to smells. “They protect and carry them like a molecular chaperone,” says Cobb, transporting them to receptor cells. But it is not known how these alleged receptor cells do the business of smelling, or even what they might look like.

Apparently fruit fly larvae can detect 45 out of 52 smells they were given, and onion fly maggots can smell 27 odours found in onions. The test is to put a bunch of larvae in a dish with a smell at one end and count how many gravitate towards the smell: a scientific version of the Guinness ad’s Cuban snail race where the protagonists slide speedily towards an overturned pint.

It is hardly surprising that research on the olfactory ability of the cabbage root fly shows that they can smell cabbages. The trouble is, it has proved impossible to tell if the maggots are reacting to all the smells, or if they can distinguish between them.

But why should maggots be able to smell anyway? Mother flies lay their eggs on prime food, be it a rotten apple or a decomposing animal, and all the maggot has to do is eat. Cobb doesn’t believe the maggots’ ability is an evolutionary hang-up; they have been around for 40 million years and if they haven’t got rid of their sense of smell by now, there must be a reason. One explanation could be that if a maggot falls off its food, it could use its sense of smell to negotiate its way back.

Another is that smell would allow maggot to discriminate between shades of decomposition. Fruit and flesh don’t decompose at the same rate, so smell could help them avoid toxic substances that build up in some areas and not others.

Forensic science relies on being able to pinpoint death by the number, type and age of maggots in the corpse: different species of maggot are attracted by specific rates of decay which they might be able to determine through their sense of smell.

S mell may also help maggots to help us inadvertently. Henry VIII used them to heal his ulcers, and the Seaman’s Mission in Greenwich also employed them for a time. The ability of maggots to facilitate wound healing was first noticed on the battlefield when maggots accidentally infected wounds. During the American Civil War, a confederate officer remarked: “I have frequently seen neglected wounds filled with maggots. as far as my experience extends, these worms only destroy dead tissues, and do not injure specifically the well parts.” The maggots might use smell to discriminate between healthy and rotting tissue.

An alternative idea is that the food the larva feeds on could influence where and on what the adult lays eggs. Once the larvae have reached a certain size, they form pupae. Inside the cocoon they dissolve completely; this molecular soup reforms as an adult fly. And yet some memories of smells learnt by the larvae are retained as adults. This seems remarkable, but the brain of the maggot is the only organ which does not dissolve and it may be that neuronal patterns laid down in the brain are preserved in the adult. But as Cobb says, these explanations are “all rather sad. It’s junior school nature study rather than science. No one knows why maggots smell.”

The research might help farmers: it might be possible to find a substance that smells so attractive to maggots, they would migrate out of their preferred food, cabbage roots, in the case of the cabbage root fly which can devastate whole fields, and could be trapped.

As for Cobb, he is following in Swammerdam’s footsteps: the Dutch scientist studied the cheese skipper fly which infests cheese.

“These mites, when they are about to become nymphs, generally desert the cheese in which they had hitherto lived, by leaping up and down, till they find, if possible, a more favourable situation.”

The maggots hold their tail in their mouth and bounce. By letting go of their tails they can jump about two feet. In Corsica and Sardinia, cheese riddled with maggots is considered a great delicacy, though not recommended by the medical establishment.

Recently Cobb attempted to cultivate these maggots by feeding them Camembert. But apparently they were not interested in French cheese.

<p>Sanjida O'Connell on the worm's turn and the lessons of the smell of grub</p>